Background: Cardiometabolic diseases (CMD) are a leading cause of morbidity and mortality. This study investigates the joint association of estimated cardiorespiratory fitness (eCRF) and biological age (BA) with incident CMD among middle-aged and older Chinese adults.

Methods: We included 2,243 participants aged ≥45 years without baseline CMD from the China Health and Retirement Longitudinal Study. eCRF was calculated using validated sex-specific formulas incorporating age, waist circumference, resting heart rate, and physical activity level. BA was estimated using eight biomarkers including lipids, renal function, inflammation, and blood pressure. Participants were classified as having high or low eCRF (top 70% vs. bottom 30%) and normal or accelerated biological aging (BA ≤ vs. > chronological age). Incident CMD was defined as new-onset diabetes, stroke, or heart disease during the follow-up period. Cox proportional hazards models were used to estimate hazard ratio (HR) and 95% confidence interval (CI), adjusting for age, sex, education, residence, BMI, smoking, drinking, and hypertension. Restricted cubic splines and subgroup analyses were conducted.

Results: During a 9-year follow-up, 707 participants developed CMD. Each SD increase in eCRF was associated with a 19% lower risk of CMD (HR = 0.81, 95% CI: 0.73–0.90), while each SD increase in BA was associated with a 25% higher risk (HR = 1.25, 95% CI: 1.15–1.35). Compared to those with high eCRF and normal aging, participants with low eCRF and accelerated aging had a significantly higher CMD risk. The joint association remained consistent across subgroups defined by age, sex, residence, smoking, drinking, and hypertension.

Conclusion: Higher eCRF and slower biological aging are independently and jointly associated with a lower risk of CMD. These findings highlight the importance of promoting physical fitness and mitigating biological aging to prevent cardiometabolic diseases in aging populations.

To be updated